Z. Kristallogr. NCS 2020; 235(1): 101–103

See Mun Lee, Kong Mun Lo and Edward R.T. Tiekink*

Crystal structure of 2-[(1E)-{[1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl]iminiumyl}methyl]-5-(dodecyloxy)benzen-1-olate, C23H39NO5

*Corresponding author: Edward R.T. Tiekink, Research Centre forCrystalline Materials, School of Science and Technology, SunwayUniversity, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia,e-mail: edwardt@sunway.edu.my. https://orcid.org/0000-0003-1401-1520See Mun Lee and Kong Mun Lo: Research Centre for CrystallineMaterials, School of Science and Technology, Sunway University,47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia

https://doi.org/10.1515/ncrs-2019-0523Received July 22, 2019; accepted October 2, 2019; availableonline October 14, 2019

AbstractC23H39NO5, monoclinic, P21/c (no. 14), a= 26.1698(4) Å,b= 9.4863(2) Å, c= 9.0929(2) Å, β= 97.376(2)°,V = 2238.67(8) Å3, Z = 4, Rgt(F)=0.0539, wRref(F2)=0.1580,T = 100(2) K.

CCDC no.: 1957130

The molecular structure is shown in the figure. Table 1contains crystallographic data and Table 2 contains the listof the atoms including atomic coordinates and displacementparameters.

Table 1: Data collection and handling.

Crystal: Yellow prismSize: 0.13×0.03×0.02 mmWavelength: Cu Kα radiation (1.54184 Å)µ: 0.68 mm−1

Diffractometer, scan mode: XtaLAB Synergy, ωθmax, completeness: 67.0°, >99%N(hkl)measured, N(hkl)unique, Rint: 27272, 4004, 0.040Criterion for Iobs, N(hkl)gt: Iobs > 2 σ(Iobs), 3452N(param)refined: 275Programs: CrysAlisPRO [1], SHELX [2, 3],

WinGX/ORTEP [4]

Source of materialThe melting point of the compound was measured on a Mel-Temp II digital melting point apparatus and was uncorrected.The IR spectrumwas recorded using a Perkin-Elmer RX1 spec-trophotometer as a Nujol mull in a KBr cell from 4000 to400 cm−1. The 1H NMR spectrumwas recorded in CDCl3 solu-tion on a Jeol JNM-ECA 400 MHz NMR spectrometer withchemical shifts relative to tetramethylsilane.

4-Dodecyloxy-2-hydroxybenzaldehyde was synthesizedaccording to a literature procedure [5]. The prepared alde-hyde (0.31 g, 1.0 mmol) was added to an ethanolic solu-tion (10 mL) of tris(hydroxymethyl)aminomethane (Tokyo

Open Access.© 2019 See Mun Lee et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 PublicLicense.

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102 | Lee et al.: C23H39NO5

Table 2: Fractional atomic coordinates and isotropic or equivalentisotropic displacement parameters (Å2).

Atom x y z Uiso*/Ueq

O1 0.89812(5) 1.10031(14) 0.50569(14) 0.0184(3)H1O 0.8900(9) 1.055(2) 0.4268(18) 0.028*O2 0.93683(5) 1.17452(14) 0.86963(15) 0.0192(3)H2O 0.9203(9) 1.236(2) 0.911(3) 0.029*O3 0.97309(5) 0.82780(15) 0.93578(15) 0.0231(3)H3O 1.0012(6) 0.829(3) 0.991(3) 0.035*O4 0.87899(6) 0.57144(14) 0.78365(15) 0.0230(3)O5 0.75800(6) 0.30758(15) 0.45315(16) 0.0247(3)N1 0.89831(6) 0.83173(16) 0.70445(17) 0.0160(3)H1N 0.9040(9) 0.7597(17) 0.764(2) 0.019*C1 0.93071(7) 0.95905(19) 0.7299(2) 0.0146(4)C2 0.94145(7) 1.0290(2) 0.5849(2) 0.0172(4)H2A 0.9698 1.0977 0.6078 0.021*H2B 0.9534 0.9558 0.5195 0.021*C3 0.90380(7) 1.05744(19) 0.8288(2) 0.0166(4)H3A 0.8708 1.0908 0.7747 0.020*H3B 0.8964 1.0065 0.9187 0.020*C4 0.98251(7) 0.9067(2) 0.8083(2) 0.0182(4)H4A 0.9997 0.8465 0.7405 0.022*H4B 1.0053 0.9878 0.8385 0.022*C5 0.86144(7) 0.8098(2) 0.5962(2) 0.0170(4)H5 0.8521 0.8854 0.5296 0.020*C6 0.83438(7) 0.6815(2) 0.5712(2) 0.0172(4)C7 0.84556(7) 0.5621(2) 0.6670(2) 0.0174(4)C8 0.81897(8) 0.4341(2) 0.6276(2) 0.0195(4)H8 0.8253 0.3535 0.6892 0.023*C9 0.78412(7) 0.4261(2) 0.5006(2) 0.0189(4)C10 0.77303(8) 0.5445(2) 0.4064(2) 0.0212(4)H10 0.7487 0.5375 0.3197 0.025*C11 0.79790(8) 0.6684(2) 0.4427(2) 0.0204(4)H11 0.7906 0.7480 0.3801 0.024*C12 0.76677(8) 0.1823(2) 0.5427(2) 0.0238(5)H12A 0.7570 0.1989 0.6428 0.029*H12B 0.8036 0.1557 0.5530 0.029*C13 0.73421(9) 0.0668(2) 0.4658(3) 0.0323(5)H13A 0.7410 −0.0217 0.5226 0.039*H13B 0.7448 0.0519 0.3662 0.039*C14 0.67641(9) 0.0967(3) 0.4485(3) 0.0383(6)H14A 0.6697 0.1840 0.3894 0.046*H14B 0.6583 0.0187 0.3911 0.046*C15 0.65341(9) 0.1135(3) 0.5903(3) 0.0396(6)H15A 0.6655 0.0345 0.6570 0.048*H15B 0.6668 0.2018 0.6388 0.048*C16 0.59630(10) 0.1175(4) 0.5752(3) 0.0480(7)H16A 0.5848 0.1952 0.5063 0.058*H16B 0.5835 0.0287 0.5264 0.058*C17 0.57043(11) 0.1349(4) 0.7065(4) 0.0597(9)H17A 0.5798 0.2295 0.7474 0.072*H17B 0.5857 0.0654 0.7806 0.072*C18 0.51451(11) 0.1220(4) 0.6989(3) 0.0540(8)H18A 0.4994 0.1906 0.6234 0.065*H18B 0.5054 0.0271 0.6585 0.065*C19 0.48748(11) 0.1401(5) 0.8267(4) 0.0707(11)H19A 0.4950 0.2370 0.8636 0.085*H19B 0.5040 0.0754 0.9041 0.085*

Table 2 (continued)

Atom x y z Uiso*/Ueq

C20 0.43222(10) 0.1204(4) 0.8214(3) 0.0542(8)H20A 0.4244 0.0245 0.7820 0.065*H20B 0.4156 0.1872 0.7464 0.065*C21 0.40593(12) 0.1355(5) 0.9530(4) 0.0708(11)H21A 0.4110 0.2342 0.9872 0.085*H21B 0.4245 0.0751 1.0311 0.085*C22 0.35122(12) 0.1044(5) 0.9484(4) 0.0739(12)H22A 0.3420 0.1169 1.0499 0.089*H22B 0.3461 0.0035 0.9228 0.089*C23 0.31410(12) 0.1865(4) 0.8462(4) 0.0554(8)H23A 0.3146 0.2851 0.8784 0.083*H23B 0.2794 0.1477 0.8466 0.083*H23C 0.3237 0.1812 0.7456 0.083*

Chemical Industry, 0.12 g, 1.0 mmol) and refluxed for 3 h. Thefiltrate was evaporated slowly until a yellow precipitate wasformed. The precipitate was recrystallized from methanol-hexane by slow evaporation to yield yellow crystals. Yield:0.16 g (39.1%).M.pt: 383–384 K. IR (cm−1) 3233 (br) ν(O—H),1634 (s) ν(C—N), 1525 (s) ν(C—O), 1047 (s) ν(C—O), 1016 (m)ν(C—O). 1H NMR (CDCl3, ppm): δ 0.86 (s, 3H, CH3), 1.24–1.79(m, 20H, CH2), 3.70–4.00 (m, 8H, OCH2), 6.40 (d, 1H, Ph—H),6.51 (d, 1H, Ph—H), 7.37 (1H, Ph—H), 8.41 (s, 1H, N= CH); OHand NH protons were not observed.

Experimental detailsThe C-bound H atoms were geometrically placed (C—H=0.95–0.99 Å) and refined as riding with U iso(H)= 1.2–1.5Ueq(C). The O- and N-bound H-atoms were located ina difference Fourier map but were refined with distancerestraints of O—H=0.84±0.01 Å and N—H=0.88±0.01 Å,respectively, and with U iso(H) set to 1.5Ueq(O) and 1.2Ueq(N),respectively. As evident from the figure, the long chain suf-fers from typical disorder. Careful modelling did not revealany chemically useful information and so, the simpler modelwas retained.

CommentIn connection with recent studies of diorganotin Schiffbases derived from tris[(hydroxymethyl)aminomethane] [6,7], largely motivated by the promising cytotoxicities theyexhibit [6], the structure of the title tris[(hydroxymethyl)aminomethane] Schiff basederivative, featuring anappendedn-dodecyl substituent, was prepared and studied crystallo-graphically.

The molecular structure is shown in the figure (50%displacement ellipsoids) and crystallography confirmsthe molecule existing as a zwitterion in the solid-state.

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Lee et al.: C23H39NO5 | 103

Proton transfer has occurred from the phenol group tothe imine-nitrogen atom (see the figure). An intramolec-ular, charge-assisted medium-strong imine-N—H· · ·O(phenoxide) hydrogen bond is evident [N1—H1n· · ·O4:H1n· · ·O4= 1.918(17) Å, N1· · ·O4= 2.639(2) Å with angle atH1n= 138.9(19)°]. The C5—N1 imine bond length is 1.303(3) Åand the configuration about this bond is E. The imine residueis co-planar with the phenyl ring to which it is connectedwiththe N1—C5—C6—C11 and N1—C5—C6—C7 torsion angles being−175.12(18) and 0.5(3)°, respectively. The alpha-methyleneatom of the n-dodecyl chain is co-planar with the phenyl ringas seen in the values of the C12—O5—C9—C8 and C12—O5—C9—C10 torsion angles of 0.9(3) and−179.71(17)°, respectively.A kink is then evident in the chain with the O5—C12—C13—C14 and C12—C13—C14—C15 torsion angles of −61.5(2) and−61.9(3)°, respectively, being indicative of – syn-clinal confor-mations. The remainingmethylene atomsof the chainhave analmost all-trans conformation with the maximum deviationin torsion angles being −169.7(2)°, for C13—C14—C15—C16.

There is a single literature precedent for the structurereported herein, that is, with amethyl rather than a n-dodecylsubstituent [8]. This is also zwitterionic andwas characterisedas a monohydrate.

In the crystal, the O1-hydroxy group forms a charge-assisted hydrogen bond with the phenoxide-O atom [O1—H1o· · ·O4i: H1o· · ·O4i = 1.766(18) Å, O1· · ·O4i = 2.5927(19) Åwith angle at H1o= 167.5(18)° for symmetry operation (i) x,3/2 − y, −1/2+ z] while the other hydroxy groups partici-pate in hydroxy—O—H· · ·O(hydroxy) hydrogen bonds [O2—H2o· · ·O1ii: H2o· · ·O1ii = 1.90(2) Å, O2· · ·O1ii = 2.7279(19) Åwith angle at H2o= 166(2)° and O3—H3o· · ·O2iii:H3o· · ·O2iii = 1.93(2) Å, O3· · ·O2iii = 2.7600(19) Å with angleat H3o= 176(3)° for (ii) x, 5/2 − y, 1/2+ z and (iii) 2 − x,2 − y, 2 − z]. The molecules assemble head-to-head toform a bi-layer, in the bc-plane, sustained by the aforemen-tioned hydrogen bonding interactions. This allows for theinter-digitation of the n-dodecyl chains.

Using established procedures [9] and Crystal Explorer17 [10], the calculated Hirshfeld surfaces were analysed aswere the full and delineated two-dimensional fingerprintplots. The presence of multiple conventional hydrogen bond-ing interactions is reflected in a significant contribution ofH· · ·O/O· · ·H contacts, that is, 15.4% to the overall surface.

This notwithstanding, by far the greatest contribution ismadebyH· · ·H contacts, at 72.9%, reflecting the hydrophobic inter-actions in the inter-layer region. The only other contribu-tion to the surface contacts of note are from H· · ·C/C· · ·Hcontacts of 10.9%, which arise largely from methylene-C3—H· · · π(phenyl) and methyl-C23—H· · · π(phenyl) interactionswithin the bi-layer constructed from the O—H· · ·O hydrogenbonding.

Acknowledgements: SunwayUniversity SdnBhd is thankedfor financial support of this work through Grant no. STR-RCTR-RCCM-001-2019.

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